diff --git a/index.html b/index.html
index 4132f60..652cdec 100644
--- a/index.html
+++ b/index.html
@@ -76,7 +76,7 @@
             
         </section>
 
-        <section id="section-2" class="section" style="display: none;">
+        <section id="section-2" class="section hidden">
             <button class="button is-link is-light" onclick="switchSection('section-1')">Torna enrere (Classe)</button>
 
             <div id="letter-container" class="buttons grid">
@@ -95,7 +95,7 @@
             </div>
         </section>
 
-        <section id="section-3" class="section" style="display: none;">
+        <section id="section-3" class="section hidden">
             <button class="button is-link is-light" onclick="switchSection('section-2')">Torna enrere (Lletra)</button>
             
             <div id="number-container" class="buttons grid">
@@ -111,7 +111,7 @@
                 <button class="button" id="number-10" data-number="10">10</button>
             </div>
         </section>
-        <section id="section-send" class="section" style="display: none;">
+        <section id="section-send" class="section hidden">
             <button class="button is-link is-light" onclick="switchSection('section-3')">Torna enrere (Número)</button>
             <br/><br/>
             <span class="has-text-weight-bold">Assignatura:</span>